During Apple’s quarterly earnings call yesterday afternoon, Tim Cook said something along the lines of “Apple has some great stuff coming in the fall.” While the comment is vague, Apple’s Q4 guidance may shine some light on when exactly we can expect to see new products.

Apple said that it expects revenue of $34 billion to $37 billion in the September quarter, with gross margins between 36 and 37%. And, according to BTIG analyst Walt Piecyk, those numbers only make sense if the company introduces some new hardware in September…

“We don’t think that Apple can hit its newly issued revenue guidance for the September quarter unless it launches new products,” Piecyk said in a note to clients. “After delivering $35 billion in revenue in the June quarter, management guided to $34-$37 billion next quarter. Revenue would more typically drop multiple billions if the company had no new products planned.”

Piecyk goes on to say that looking at the margin guidance, it’s likely that the new product launch this quarter will be an iPhone—not an iPad, which pulls in lower margins. “While new iPhones bring in lower profit margins initially, they are still notably higher than iPad margins.”

And Morgan Stanley analyst Katy Huberty echoes the theory. Huberty also sent out a note to investors this afternoon, citing Apple’s lack of transparency in gross margin influences, and wider than normal revenue guidance range of $3B in Q4 as evidence of new products.

Apple’s fourth quarter ends at the end of September. So if these guys are correct, we can expect an Apple press event sometime before that. The company is widely expected to introduce a new iPhone this fall, alongside a budget handset and multiple iPad/iPod refreshes.